Grains are a valuable source of micro and macro nutrients, e.g., carbohydrates, proteins, vitamins, antioxidants and both soluble and insoluble fiber, but raw grain, e.g., barley, maize, oat, rice, sorghum, triticale and wheat, is generally unpalatable and not easily digested. Thus grain is usually processed by cooking to a form that is more easily digested and also possesses pleasing organoleptic properties of appearance, aroma, taste and texture. The nutritional value and organoleptic properties of the processed grain food product and their ability to be stored for long periods of time depend on a combination of factors, e.g., on the type of grain that is processed, e.g., whether the grain possesses high levels of fiber and antioxidants, the levels of lipase and peroxidase, the types and amounts of starch in the processed grain, e.g., amylopectin or amylose, and the steps used to process the grain.
Grains are a good source of fiber and a diet high in fiber has been associated with various health benefits, e.g., lowering cholesterol, modulating blood sugar levels, which is an important consideration for persons with diabetes, and reducing the risk of colin cancer (LaBell, Healthy Barley Foods Multiply, 87 (November 1997). High serum cholesterol is a recognized risk factor for heart disease and is reversible by diet in a majority of cases (Connor and Connor, “The Dietary Prevention and Treatment of Coronary Heart Disease.” In: Coronary Heart Disease, W. E. Connor and J. D. Bristow, Eds. J. B. Lippincott, Philadelphia, 1984). Three factors modified in a diet to reduce cholesterol include: reducing total fat, increasing the ratio of polyunsaturated to saturated fatty acids, and consuming soluble dietary fiber. Dietary fiber consists of a mixture of components which vary in degree of solubility in water and soluble fibers are well-documented as having beneficial hypocholesterolemic benefits (Newman et al., Cereal Foods World, 34(10)883-886 (1989)). Components that are considered generally soluble in water include pectin, gums, and mixed linked (1-3) (1-4)-β-glucans, such as, e.g., the β-glucans found in the oat bran and in endosperm cell walls of barley. About 70% of the barley endosperm cell walls are β-glucans. However, the hypocholesterolemic effects of isolated β-glucans and the hypocholesterolemic effects of certain milling fractions of grain are not the same as those of a wholegrain product, which contains intact endosperm cell walls (Newman et al., “The Hypocholesterolemic Function of Barley β-Glucans,” Cereal Food World, 34(10):883-884, 1989).
Grains also provide antioxidants, which are thought to be protective against cardiovascular disease and various cancers. Tocopherols, e.g., Vitamin E, is a potent antioxidant. In its natural food state, Vitamin E is actually a family of several different tocopherols, alpha, beta, epsilon, and gamma. Animal and in vitro studies indicate that Vitamin E supplementation reduces the risk of chemical- and radiation-induced cancers.
The starch makeup of grains can affect the organoleptic characteristics of processed grains. Grains contain a combination of two kinds of starch, amylose and amylopectin. Amylose is a straight chain glucose polymer having α-1,4 linkages. Amylopectin is a branched chain glucose polymer with 1-6 linkages at the branching points. Grains designated “waxy” or “non-waxy” differ in their content of amylose and amylopectin starches. Grains having 10% or less amylose are designated “waxy.” Waxy varieties exist for barley, maize, oat, rice, sorghum, triticale and wheat, and some have been used previously in a variety of methods to produce palatable and digestible food products.
Unlike raw grains, which may be stored for long periods of time without deteriorating, provided the grain is kept dry, food products from processed grains are often subject to mold and bacterial growth as well as oxidative and enzymatic degradation. Thus many processed grains and food products comprising processed grains cannot be stored for long periods without becoming rancid and losing their pleasing appearance, aroma, taste and texture, unless they are treated with preservatives.
U.S. Pat. No. 2,526,792 to Aldeman discloses the preparation of a pearled waxy barley-based cooked and puffed product. The method described does not include steps that would make the product shelf stable for prolonged periods of time.
U.S. Pat. No. 2,930,697 to Miller discloses a process wherein grain, e.g., wheat, oat, sorghum and rye is soaked to increase its moisture level, flattened to break the epidermis and endosperm and then cooked with steam or with water to uniformly gelatinize the starch. Miller does not disclose the use of waxy grains.
U.S. Pat. No. 4,603,055 to Karowski et al. is directed to the production of cereal flakes that are thicker than normal toasted flakes and have a high flake integrity that withstands packaging, shipping and dehydration cooking. Karowski et al. produce a multiple grain based flaked cereal from a plurality of grain types that are cut into pieces and then steamed and tempered for 15-20 minutes but the grains are only partially gelatinize the grain prior to rolling into a flake.
U.S. Pat. No. 5,391,388 to Lewis et al. discloses the preparation of a waxy barley-based porridge-like breakfast cereal wherein less than 30% of the starch is gelatinized. This is a partially gelatinized, partially cooked quick cooking hot cereal. The patent also discloses a non-crispy cold breakfast cereal food.
U.S. Pat. No. 5,360,619 to Alexander relates to cereal foods ingredients from waxy barley. The cereal food products of this patent are not gelatinized throughout and the grain is pearled and thus lacks the outer parts of the grain. The outer part of the grain is a source of fiber and therefore by pearling, the grain reduces the proportion of beneficial fiber in the cereal food ingredients of this patent.
European patent application 0 338 239 to inventors Short and Wilkinson, describes a method for producing a microwaveable half product and a puffed food product from flour of one or more grains, one of which being a whole ground waxy maize. While the process disclosed therein fully gelatinizes the starch, the product is prepared from a dough and the products are not storage stable. They rapidly undergo enzymatic and oxidative rancidity resulting in a product having a taste, odor and texture that is not acceptable to consumers.
International application WO 96/19117 (inventor Lewis) discloses a method that includes a step for fully gelatinizes waxy grains, either whole or subdivided. However, the product cannot be stored for prolonged periods without becoming rancid without additives to inhibit the development of rancidity.
U.S. Pat. No. 4,737,371 discloses a treatment for protecting grain from enzymatic deterioration by inactivation of lipolytic and oxidative enzymes prior to milling into a shelf stable high fat flour. The grain is soaked for a prolonged period to raise the moisture content to 13-17%, then quickly heated, cooled and stored or milled into a flour. The patent does not disclose the use of waxy grains.
U.S. Pat. No. 4,413,018 to Webster et al. discloses a process for imparting shelf stability to oat groats wherein the groats are heated for a time and temperature sufficiently intense to inactivate the enzymes with causing the oxidative reaction process to go forward. The oats are treated to reduce the moisture level by heating over a period of 1-2 hours, then slowly cooled and thereafter steamed or boiled for 5-10 minutes. This patent also does not disclose waxy grains.
U.S. Pat. Nos. 6,139,894 and 6,042,867 both to Hoshino et al. discloses the use of a flour blend that comprises a waxy wheat flour prepared from a waxy wheat having less than 10% amylose. The generation of this waxy wheat is described in Japanese Patent Application Laid Open No. 6-125669. The patents disclose the use of waxy wheat flours in bread cakes and noodles as well as deep fried foods, steamed Chinese Manju, dough sheets, okonomi-yaki and takoyaki and that the products prepared from the waxy wheat flour blends have particularly desirable properties. The waxy wheat flour is always used as a component in a flour blend and is never more than 80% of the blend. The inventors do not describe a process for cooking the waxy wheat prior to milling.
While heating may seem a straightforward alternative to deactivating enzymes, U.S. Pat. No. 6,156,365 to Liwszyc discloses that some heat treatments, while capable of inhibiting the enzyme, accelerate the oxidative rancidity. Liwszyc discloses a process for preparing a fully and uniformly gelatinized hulled non-waxy oat comprising adding water to the hulled oats and cooking the oats for a time and at a temperature to fully gelatinize the oats. This patent deactivates active enzymes in oat bran by steaming hulled oats in the presence of heat (100° C., 212° F.) for 1 to 3 hours and discloses that further harsh treatment of hulled oats leads to the destruction of antioxidants and shortening the shelf life of the finished product. The flakes produced by the described method are reported to be more water absorbent than traditional oat flakes. This patent does not disclose waxy grains.
The methods described herein are suitable for application to waxy grains that may or may not be pearled but are particularly useful for processing waxy grains that are high in lipases and peroxidases, e.g., waxy wheats. The processes of this invention produce a digestible, palatable waxy grain food product that is a storage stable, gelatinized throughout, and that is organoleptically acceptable to consumers. In addition to being storage stable, the products prepared from grain that is not pearled also provide the amounts of fiber and tocopherols found naturally in grain as harvested as well as high levels of antioxidants. This is especially true for grains where the fibers are found in the bran of the grain, e.g., in oat bran.